Method of mounting marine propellers



Oct. 17, 1939. A. A. HAYFIELD METHOD OF MOUNTING MARINE PROPELLERS Filed Sept. 13, 1937 fi/fred/Z Hay/add I ATTORNEYS Patented Oct. 17, 1939 UNITED STATES PATENT OFFICE MIETHCD OF MOUNTING MARINE PROPELLERS 1 Claim.

This invention relates to marine propulsion and more particularly to the arrangement of twin propellers of the multiple blade screw type and propeller shafts therefor with relation to the longitudinal axis of a boat so as to secure more effective thrusts on the water at a slower speed of rotation of the propellers and to eliminate power loss, commonly known as slippage and excessive turbulence of the water by the propellers.

With these and other objects in view, this invention consists in certain novel features of construction, combination and arrangement of parts to be hereinafter more fully described and claimed.

For a complete understanding of my invention, reference is to be had to the following description and accompanying drawing, in which:

Figure 1 is a top plan view of the stern portion of a boat, partly broken away, showing the relative relation of the propellers to each other and to said stern portion of said boat and the keel of the latter.

Figure 2 is a sectional view taken on the line 2-2 of Figure 1.

Referring in detail to the drawing, the numerals l and 2 indicate twin propellers and 3 and 4 the shafts of said propellers. The shafts may be connected in any suitable manner with a power source (not shown) so that the propellers will be rotated in opposite directions as indicated by the arrows in Figure 1. Each propeller may have three or more blades, each blade having a pitch of approximately 45 degrees.

The shafts 3 and 4 are mounted on the boat 5 in diverging relation of approximately 90 degrees and also are inclined at an angle of approximately 45 degrees to the forward direction of travel of the boat. The shafts diverge from the forward ends towards the rear ends and are inclined upwardly from the rear ends towards the forward ends, which positions the propellers at approximately degree angle to the direction of travel of the boat at opposite sides of the keel B of the boat and inclined at approximately 45 degrees to vertical lines passing through the hubs of said propellers. 6

The propellers thus located with respect to the boat and its forward direction of travel, will have more effective thrusts on the water at a slower speed of rotation over the conventional location of propellers on boats and with less slip- 10 page and turbulence of the water. During the rotation of the propellers in opposite directions, the blades when passing through the lower quadrant of the circle of rotation will have the maximum thrust on the water and at right angles to 16 the direction of travel of the boat while the blades when passing through the upper quadrant of the circle of rotation will have a feathering action on the water reducing to a minimum thrusts on the water which would have a tendency 20 to retard the forward progress of the boat, consequently permitting propulsion of the boat at a faster rate of speed with motive power of less horsepower.

What is claimed is: 25

In combination with a boat having a keel, propeller shafts mounted on the boat for rotation in opposite directions and arranged in diverging relation and at opposite sides of the keel and inclining downwardly from the forward ends to- 30 wards the rear ends thereof, and propellers secured on said shafts substantially rearwardly of the aft end of the boat, said propellers positioned at an angle of approximately 45 to the forward direction of travel of the boat and in- 35 clined at an angle of approximately 45 to vertical lines passing through the propellers by the relative arrangement of the shafts and the relative arrangement of the latter with respect to the boat. 40

ALFRED A. HAYFIELD. 

